Power-driven gear operated wrench



Nov. 18, 1952 E. H. SHAFF POWER-DRIVEN GEAR OPERATED WRENCH Filed March 8, 1950 IIIlIII/l Wm svnedt' Q1. 5k

1 CW,@M ,a/

- damn Patented Nov. 18, 1952 POWER-DRIVEN GEAR OPERATED WRENCH Ernest H. Shafi, Hamilton, Ind., assignor to Keller Tool Company, Grand Haven, Mich., a corporation of Michigan Application August 8, 1950, Serial No. 178,288

6 Claims.

The present invention relates to power driven wrenches and has for a general object the provision of an improved positive drivin connection between the motor of the tool and the socket element so as to achieve highly efiicient opera: tion while at the same time attaining an exceedingly simple and sturdy construction which permits of economical manufacture.

A more specific object is to provide a modified form of crown gear drive for the socket element of a power wrench wherein the forms of the gear elements are so correlated that non-reversibility obtains to the end that a positive lock between the tool spindle and the socket element is provided for manual application of force in the tightening or final setting action.

Still another object is to provide a drive of the character set forth in which the number of parts required is minimized and in which the parts are advantageously arranged whereby the dimensions of the nose portion of the tool and the number of moving parts that are exposed are minimized.

The objects of the invention thus generally set forth together with other objects and ancillary advantages are attained by the construction and arrangement shown by way of illustration in the accompanying drawing, in which:

Figure 1 is a fragmentary perspective view of the forward end portion of a power wrench incorporating the features of the present invention. a

Fig. 2 is a. central longitudinal section taken substantially in the plane of line 2-2 in Fig. 1.

Figs. 3, 4 and 5 are fragmentary transverse sectional views taken substantially in the plane of line 33 in Fig. 2 and illustrating various relative positions of the gear elements of the instant drive.

While the invention is susceptible of various modifications and alternative constructions, there is shown in the drawing and will herein be described in detail the preferred embodiment, but it is to be understood that it is not thereby intended to limit the invention to the specific form disclosed, but the intention is to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims. By way of illustration, there isshown in the drawing a portable wrench comprising a power unit Ill embodying a rotary motor which is enclosed within a casing I2, and a tool head I4 connected with the power unit and extending longitudinally therefrom. The drive motor, which has not been illustrated in detail, is preferably of the non-reversible, rotary, fluid-pressure actuated type and includes a rotor which is fast on a spindle I6. The latter is journaled in a bearing I8 which, in turn, is held in an end plate fixed within the casing I2 in position to close the forward end of the motor cylinder 22. At its forward end the casing I2 is provided with an internal screw thread 24 for the reception of the base portion 26 of the tool head I4.

The tool head I4 includes an elongated fiat portion or nose 28 which, as shown, is integrally formed with the base portion 26 and which serves as a carrier for a hexagonal socket 30. It will be apparent that other tool elements may be substituted for the socket 30 as may be desired for the accommodation of various forms of threaded fastening elements.

On opposite sides of the nose 28 is secured a pair of similar bearing plates 32, the nose and the plates being suitably apertured to receive mounting screws 34. Preferably, the inner ends of the bearing plates are provided with longitudinally disposed notches 36, and the nose 28 is suitably rabbeted as at 38 to receive the rearwardly extending portions of the end plates lying on each side of the notches 36. This construction prevents loosening of the end plates by torsional strains to which they are subjected in the use of the tool.

The outer ends of the plates 32 project beyond the end of the nose 28 and are adapted to receive the socket element 30 therebetween. For this purpose these outer ends are provided with coaxially disposed apertures 40 and the socket is fashioned to provide hub portions 42 of a diameter corresponding to that of the apertures 40 for journaling therein. Intermediate its ends the socket 30 is of a diameter somewhat larger than that of the hub portions 42 and of a thickness substantially the same as the spacing between the inner faces of the plates 32. Thus, there .are

formed bearing surfaces 44 for engagement with the plates 32 (Fig. 2).

In accordance with the invention, a drive gearing is employed which partakes generally of the nature of crown gearing which for power actuation of the tool provides a positive and efficient connection between the power source and the socket element, yet is especially constructed to provide a positive lock for the socket element to permit of manual application of force to finally set a fastening element. In the illustrative embodiment, the socket element has. a circumferentially arranged series of teeth 48 thereon disposed substantially parallel to the socket axis. These teeth form in effect an annular gear rigid with the socket element for coaction with a driving gear or pinion 50 having two teeth and which is disposed on an axis substantially at right angles to that of the socket element. The circle defined by the tips of the teeth 48 is disposed at or beyond the axis of the pinion 50 but is located in spaced relation to one of the bearing plates 32.

Preferably, the driving gear 59 is integrally formed with the shaft 52, and the two teeth 5| are spaced apart and project longitudinally beyond the outer end of the shaft 52 on diametrically opposite sides of its axis.

To enhance the operation of the instant drive gearing, the teeth 48 are formed with substantially straight sides adjacent their roots and with flat-sided triangular tip portions. The teeth 5! of the pinion 59 have the portions thereof that are oppositely disposed with respect to each other also formed with flat angularly disposed faces which are complementary to the triangular tip portions of the socket teeth 48.

While the size of the socket and the driven gear element and the driving pinion may vary and the number of teeth of the driven gear element may be altered, a driving connection of the following character has been found to operate satisfactorily: A driven gear element of substantially 1 /4 inches in major diameter having fifteen teeth thereon with the fiat surfaces of their tip portions tapered at an angle of 30 with respect to the socket axis has been utilized in conjunction with a driving gear or pinion having the tips of its two teeth separated by of an inch with the complementary tip surfaces disposed at an angle of 60 with respect to a diametrically disposed plane passing centrally through each tooth and having a tooth width of slightly less than the separation between the teeth of the socket element, in this instance, approximately of an inch.

The shaft 52 is rotated by the power unit H through the medium of a splined connection 58 between the forward end of the motor spindle and the rear end of the shaft. In order to insure that there is clearance between the tips of the pinion teeth 5| and the body of the socket element 30 above the teeth 43 thereon, the shaft 52, which extends longitudinally of the tool head (4 and is journaled in a passage 59 therein, has its axis inclined slightly with respect to and normal to the socket axis (Fig. 2), the axes, however, lying in a common plane.

In use, a nut or other threaded fastening element is run or initially tightened by power actuation of the tool. It is apparent that rotative force is transmitted from the pinion 50 to the socket 30 always in a direction substantially tarrgent'ial to the socket so as to produce rotation thereof.

After a fastening element has been run down to the stall point of the motor of the power unit H), the fastening element is driven home manually by swinging the tool bodily about the axis of the socket element 30. Rotation of the socket element relative to the tool is prevented by engagement of the socket teeth 48 with'the teeth 5| of the driving gear 50 in two particular positions of the latter. It will be observedthat upon application of manual force for swinging the tool about the socket axis with the. socketelement and driving gear teeth in the positions shown in Fig. 3,.since the socket is held stationary by the fastening element, the applied force is transmitted from the socket element 30 to the driving gear 50 at a point substantially removed from the axis of the driving gear. Thus a turning movement of the driving gear is produced. As this turning move-' ment continues, the extremities of the angularly disposed tip faces of the teeth 5| of the driving ear 50 and of the teeth 48 on the socket element 30 are brought into engagement (Fig. 4). Upon continued application of manual force, the gear elements 48 and 50 assume the relative positions shown in Fig. 5, which is in effect a dead-center position of the driving gear. In such relative positions, all of the force applied to the tool and thus to the socket element 30 is transmitted to the driving gear 50 adjacent the tips of the engaged teeth and in a direction substantially radially outward from the turning axis of the driving gear 50 and its shaft 52. Force applied in such direction produces no force couple about the axis of the shaft. Thus there is produced no turning movement of the shaft and there is a positive lock between the shaft driving gear and socket element.

It is apparent from the foregoing that upon manual application of force to bodily swing the tool about the socket axis, movement of the socket 38 with respect to the tool occurs only until the relative positions of the teeth 48 and 5| as shown in Fig. 5 are attained in which positions the socket 30 is positively locked against movement with respect to the tool. In such locked condition, obviously, the manually applied force is imparted to the fastening element to finally set it.

Should it be desired to use the instant tool in the manner of a ratchet wrench, repositioning for further tightening without necessity of removing the socket from the fastening element may be accomplished by momentarily admitting. fluid pressure to drive the motor. With the fastening element tight and thus stationary, the socket element is prevented from rotating. Therefore, upon admission of pressure fluid reverse rotation of the power unit It and the tool head M relative to the socket element 30 and about its rotational axis is produced.

While the operation thus described has been directed to the running and setting of conventionally threaded fastening elements, the tool can also be used for running and setting reversely threaded elements and for the removal of either form. In the latter application, manual operation is employed for initially loosening the fastening element. To accomplish these ends, the tool need only be inverted or turned over from the positions illustrated in the drawings. It will be apparent therefore that this feature of the instant construction permits the use of a nonreversible motor to drive the tool and such form is inherently less complicated and of greater rela tive power output than a reversible motor of comparable size.

From the foregoing, therefore, it will be apparent that the present invention provides an improved cr-own gear drive for power Wrenches the moving elements of which are almost completely concealed; whichbecause of the correlation be-' tween the driving gear teeth and those on the socket element permits power actuation for the running of threaded fastening elements and provides a positive lock for the socket element so that a fastening element can be finally set to the desired degree of tightness by manual application of force to the tool. Moreover, the presenttool embodies advantages such as reversibility for either setting or removing a threaded element though it is powered by any suitable rotary motor of the non-reversible type.

I claim as my invention:

1. In a power wrench having a rotatable tool member, drive means for the tool member comprising an annular driven gear element rigid with respect to the tool member and having a circumferentially arranged series of teeth thereon disposed in substantially parallel relation to the axis of the tool member, and a driving gear element having its axis disposed substantially at right angles to the axis of the tool member, said axes lying in a common plane, said driven gear element having two equidistantly spaced and diametrically opposed teeth meshing with the teeth of said driven gear element, the tips of the teeth of said driven gear element extending at least to the axis of said driving gear element.

2. In a power wrench having a tool member and a drive shaft journaled for rotation on axes disposed in a common plane and substantially at right angles to each other, non-reversible drive means for the tool member comprising an annular driven gear element secured in coaxial relation with respect to the tool member and presenting a series of teeth circumferentially spaced about the tool member terminating intermediate its ends, and a driving gear element rigid with respect to the drive shaft and having a pair of equidistantly spaced diametrically disposed teeth projecting outwardly therefrom and meshing with the driven gear teeth, the teeth of said driven gear having substantially triangular tip portions and the teeth of said driving gear havin; their oppositely disposed portions of triangula cross-section so as to present flat complementary surfaces for engagement in certain relative positions of the gear elements in which positions the tool member is locked with respect to the wrencl to permit manual application of force to finall set the fastening element.

3. In a power wrench, the combination comprising a nose portion, a tool member journaled for rotation on said nose portion, and a self-locking drive for said tool member, said drive including a crown gear rigid with said tool member, a meshing pinion, and a shaft journaled in said nose portion and mounting said pinion for rotation about an axis extending substantially at right angles to the axis of said crown gear, the

axes of said crown gear and said pinion being disposed in a common plane, the axis of the.

pinion being disposed between the tip and root circles of the crown gear.

4. A self-locking drive comprising a crown gear and a meshing pinion journaled for rotation about axes normal to each other in a common plane and located with the axis of said pinion between the tip circle and the root circle of said crown gear.

5. In a power wrench having a motor and a nose portion with a tool member rotatably supported thereon and adapted to be driven by the motor, the combination comprising a nose element, a pair of bearing plates rigid with said nose element and adapted to journal the tool I member, and driving means for the tool element including a crown gear operatively associated with the tool element and a meshing pinion operatively connected to the motor, said crown gear being coaxially disposed with respect to the tool member and the tip circle thereof being spaced from one of said bearing plates, said crown gear and said pinion being journaled for rotation on axes substantially normal to each other and lying in a common plane, the tip circle of said crown gear being located at or beyond the axis of said pinion.

6. A self-locking drive comprising a crown gear and a meshing pinion journaled for rotation about axes normal to each other in a common plane and located with the axis of said pinion between the tip and root circles of said crown gear, said pinion having two diametrically disposed, outwardly projecting teeth having inner surfaces lying substantially parallel to the pinion axis and arcuate outer surfaces tapering outwardly toward the pinion axis, and each of said crown gear teeth having the pinion engaging faces thereof substantially parallel to a radius passing centrally therethrough.

ERNEST H. SHAFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 748,653 Richter Jan. 5, 1904 1,384,811 Strand July 19, 1921 1,750,957 Fowler Mar. 18, 1930 2,307,886 Hansson Jan. 12, 19 43 

